[buteo-sync-plugins-social] Purge ophan 'ghost' events. Contributes t…

…o JB#52608

During ghost event cleanup, any orphans that don't belong to any
notebook are deleted. This also purges them so they no longer exist in
the database after the sync.

src/google/google-calendars/googlecalendarsyncadaptor.cpp

@@ -1117,7 +1117,7 @@ void GoogleCalendarSyncAdaptor::finalCleanup()
         if (foundOrphans == 0) {
             setGhostEventCleanupPerformed();
             SOCIALD_LOG_INFO("orphan cleanup completed without finding orphans!");
-        } else if (m_storage->save()) {
+        } else if (m_storage->save(mKCal::ExtendedStorage::PurgeDeleted)) {
             setGhostEventCleanupPerformed();
             SOCIALD_LOG_INFO("orphan cleanup deleted" << foundOrphans << "; storage save completed!");
         } else {